Bacterial phyla
Bacterial phyla constitute the major lineages of the domain Bacteria. While the exact definition of a bacterial phylum is debated, a popular definition is that a bacterial phylum is a monophyletic lineage of bacteria whose 16S rRNA genes share a pairwise sequence identity of ~75% or less with those of the members of other bacterial phyla.
It has been estimated that ~1,300 bacterial phyla exist. As of May 2020, 41 bacterial phyla are formally accepted by the LPSN, 89 bacterial phyla are recognized on the Silva database, dozens more have been proposed, and hundreds likely remain to be discovered. As of 2017, approximately 72% of widely recognized bacterial phyla were candidate phyla.
The rank of phylum has been included in the rules of the International Code of Nomenclature of Prokaryotes, using the ending –ota for phylum names that must be based on the name of a genus as its nomenclatural type.
List of bacterial phyla
The following is a list of bacterial phyla that have been validly published as of December 2023.| Phylum | Alternative names | Group | Known classes | Notes |
| "Abditibacteriota" | FBP | 1 | ||
| Acidobacteriota | "Acidobacteria" | 5 | ||
| Actinomycetota | "Actinobacteria" | Bacillati | 6 | |
| Armatimonadota | "Armatimonadetes", OP10 | Bacillati | 3 | |
| Atribacterota | OP9, JS1 | 1 | ||
| Aquificota | "Aquificae" | 3 | ||
| Bacteroidota | "Bacteroidetes" | FCB group | 6 | |
| Balneolota | 1 | |||
| Bdellovibrionota | 3 | |||
| Caldisericota | OP5, "Caldiserica" | FCB group | ||
| Calditrichota | FCB group | |||
| Campylobacterota | 2 | |||
| Chlamydiota | "Chlamydiae" | PVC group | 1 | |
| Chlorobiota | "Chlorobi" | FCB group | 1 | |
| Chloroflexota | "Chloroflexi" | Bacillati | ||
| Chrysiogenota | "Chrysiogenetes" | |||
| Coprothermobacterota | ||||
| Cyanobacteriota | Cyanobacteria | Bacillati | 2 | |
| Deferribacterota | Deferribacteres | |||
| Deinococcota | Deinococcus–Thermus | Bacillati | 1 | |
| Dictyoglomota | Dictyoglomi | |||
| Elusimicrobiota | Elusimicrobia, OP7, Termite Group 1 | |||
| Fibrobacterota | "Fibrobacteres" | FCB group | ||
| Bacillota | "Firmicutes" | Bacillati | 9 | |
| Fusobacteriota | "Fusobacteria" | 1 | ||
| Gemmatimonadota | Gemmatimonadetes | FCB group | ||
| Ignavibacteriota | "Ignavibacteria", ZB1 | FCB group | ||
| Kiritimatiellota | ||||
| Lentisphaerota | "Lentisphaerae", vadinBE97 | PVC group | ||
| "Marinimicrobia" | SAR406, Marine Group A | FCB group | ||
| Myxococcota | 3 | |||
| Nitrospinota | "Nitrospinae" | |||
| Nitrospirota | "Nitrospirae" | |||
| Planctomycetota | "Planctomycetes" | PVC group | ||
| Pseudomonadota | "Proteobacteria" | |||
| Rhodothermota | ||||
| "Saccharibacteria" | TM7 | CPR; Saccharibacteria-related CPR | ||
| Spirochaetota | "Spirochaetes" | |||
| Synergistota | "Synergistetes" | |||
| Mycoplasmatota | "Tenericutes" | |||
| Thermodesulfobacteriota | "Thermodesulfobacteria" | |||
| Thermomicrobiota | "Thermomicrobia" | |||
| Thermotogota | "Thermotogae", OP2, EM3 | |||
| Verrucomicrobiota | "Verrucomicrobia" | PVC group |
The following is a list of candidate phyla that have not been cultured.
| Phylum | Alternative Names | Group | Notes |
| "Absconditabacteria" | SR1 | CPR; Gracilibacteria-related CPR | |
| ABY1 | OD1-ABY1 | CPR; Parcubacteria | |
| "Aerophobota" / "Aerophobetes" | CD12, BHI80-139 | ||
| "Andersenbacteria" | RIF9 | CPR; Parcubacteria; Parcubacteria 4-related | |
| "Aminicenantota" | OP8 | ||
| "Berkelbacteria" | ACD58 | CPR; Saccharibacteria-related CPR | |
| "Bipolaricaulota" | OP1, "Acetothermia" | ||
| "Blackburnbacteria" | RIF35 | CPR; Microgenomates | |
| "Brennerbacteria" | RIF18 | CPR; Parcubacteria; Parcubacteria 3 | |
| "Brownbacteria" | CPR; Parcubacteria; unclassified Parcubacteria | ||
| "Buchananbacteria" | RIF37 | CPR; Parcubacteria; Parcubacteria 1 | |
| "Campbellbacteria" | CPR; Patescibacteria; Parcubacteria; Parcubacteria 4 | Seems to be polyphyletic; 2 clades | |
| "Cloacimonetes" | WWE1 | FCB group | |
| "Coatesbacteria" | RIF8 | ||
| "Collierbacteria" | CPR; Patescibacteria; Microgenomates | ||
| "Colwellbacteria" | RIF41 | CPR; Parcubacteria; Parcubacteria 3 | |
| "Curtissbacteria" | CPR; Patescibacteria; Microgenomates | ||
| "Dadabacteria" | No | ||
| "Daviesbacteria" | CPR; Patescibacteria; Microgenomates | No | |
| "Delphibacteria" | FCB group | No | |
| "Delongbacteria" | RIF26, H-178 | No | |
| "Dependentiae" | TM6 | ||
| "Dojkabacteria" | WS6 | CPR; Microgenomates-related CPR | |
| "Dormibacteraeota" | AD3 | ||
| "Doudnabacteria" | SM2F11 | CPR; Parcubacteria; Parcubacteria 1-related | |
| "Edwardsbacteria" | RIF29, UBP-2 | ||
| "Eisenbacteria" | RIF28 | FCB group | |
| "Eremiobacteraeota" | WPS-2, Palusbacterota | ||
| "Falkowbacteria" | CPR; Patescibacteria; Parcubacteria; Parcubacteria 1 | ||
| "Fermentibacteria" | Hyd24-12 | ||
| "Fertabacteria" | CPR; Gracilibacteria-related CPR | ||
| "Firestonebacteria" | RIF1 | ||
| "Fervidibacteria" | OctSpa1-106 | ||
| "Fischerbacteria" | RIF25 | ||
| "Fraserbacteria" | RIF31 | ||
| "Glassbacteria" | RIF5 | No | |
| "Giovannonibacteria" | CPR; Patescibacteria; Parcubacteria; Parcubacteria 4-related | No | |
| "Gottesmanbacteria" | CPR; Patescibacteria; Microgenomates | No | |
| "Gracilibacteria" | GN02, BD1-5, SN-2 | CPR; Patescibacteria; Gracilibacteria-related CPR | No |
| "Gribaldobacteria" | CPR; Parcubacteria; Parcubacteria 2 | No | |
| "Handelsmanbacteria" | RIF27 | No | |
| "Harrisonbacteria" | RIF43 | CPR; Parcubacteria; Parcubacteria 3 | No |
| "Howlettbacteria" | CPR; Saccharibacteria-related CPR | No | |
| "Hugbacteria" | CPR; Parcubacteria; unclassified Parcubacteria | ||
| "Hydrogenedentes" | NKB19 | ||
| "Jacksonbacteria" | RIF38 | CPR; Parcubacteria; Parcubacteria 1 | |
| "Jorgensenbacteria" | CPR; Patescibacteria; Parcubacteria; Parcubacteria 3 | ||
| "Kaiserbacteria" | CPR; Patescibacteria; Parcubacteria; Parcubacteria 4 | ||
| "Katanobacteria" | WWE3 | CPR; Microgenomates-related | |
| "Kazanbacteria" | Kazan | CPR; Saccharibacteria-related CPR | |
| "Kerfeldbacteria" | RIF4 | CPR; Parcubacteria; Parcubacteria 1 | |
| "Komeilibacteria" | RIF6 | CPR; Parcubacteria; Parcubacteria 1 | |
| "Kryptonia" | |||
| "Krumholzibacteriota" | |||
| "Kuenenbacteria" | CPR; Patescibacteria; Parcubacteria; Parcubacteria 1 | ||
| "Lambdaproteobacteria" | RIF24 | Proteobacteria | |
| "Latescibacteria" | WS3 | FCB group | |
| "Levybacteria" | CPR; Patescibacteria; Microgenomates | No | |
| "Lindowbacteria" | RIF2 | CPR; Saccharibacteria-related CPR | No |
| "Liptonbacteria" | RIF42 | CPR; Parcubacteria; Parcubacteria 3 | No |
| "Lloydbacteria" | RIF45 | CPR; Parcubacteria; Parcubacteria 4 | No |
| "Magasanikbacteria" | CPR; Patescibacteria; Parcubacteria; Parcubacteria 1 | No | |
| "Margulisbacteria" | RIF30 | No | |
| "Melainabacteria" | |||
| "Microgenomates" | OP11 | CPR; Patescibacteria | |
| "Modulibacteria" | KSB3, GN06 | ||
| "Moranbacteria" | OD1-i | CPR; Patescibacteria; Parcubacteria; unclassified Parcubacteria | |
| "Muproteobacteria" | RIF23 | Proteobacteria | |
| NC10 | |||
| "Nealsonbacteria" | RIF40 | CPR; Parcubacteria; Parcubacteria 2 | |
| "Niyogibacteria" | RIF11 | CPR; Parcubacteria; Parcubacteria 4-related | |
| "Nomurabacteria" | CPR; Patescibacteria; Parcubacteria; Parcubacteria 1 | ||
| "Omnitrophica" | OP3 | PVC group | |
| "Pacebacteria" | CPR; Patescibacteria; Microgenomates | ||
| "Parcubacteria" | OD1 | CPR | |
| "Parcubacteria" 1 | CPR; Parcubacteria | ||
| "Parcubacteria" 2 | CPR; Parcubacteria | ||
| "Parcubacteria" 3 | CPR; Parcubacteria | ||
| "Parcubacteria" 4 | CPR; Parcubacteria | ||
| "Parcunitrobacteria" | CPR; Parcubacteria; unclassified Parcubacteria | ||
| PAUC34f | sponge‐associated unclassified lineage | FCB group | |
| "Peregrinibacteria" | PER | CPR; Gracilibacteria-related CPR | |
| "Peribacteria" | CPR; Gracilibacteria-related CPR | ||
| "Poribacteria" | PVC group | ||
| "Portnoybacteria" | RIF22 | CPR; Parcubacteria; Parcubacteria 4-related | |
| "Raymondbacteria" | RIF7 | ||
| Riflebacteria | RIF32 | ||
| "Roizmanbacteria" | CPR; Patescibacteria; Microgenomates | ||
| "Rokubacteria" | |||
| "Ryanbacteria" | RIF10 | CPR; Parcubacteria; Parcubacteri 4-related | |
| "Saltatorellota" | |||
| "Schekmanbacteria" | RIF3 | Proteobacteria | |
| "Shapirobacteria" | CPR; Patescibacteria; Microgenomates | ||
| "Spechtbacteria" | RIF19 | CPR; Parcubacteria; Parcubacteria 2 | |
| "Staskawiczbacteria" | RIF20 | CPR; Parcubacteria; Parcubacteria 2 | |
| "Sumerlaeota" | BRC1 | ||
| "Sungbacteria" | RIF17 | CPR; Parcubacteria; Parcubacteria 4-related | |
| TA06 | |||
| "Tagabacteria" | RIF12 | CPR; Parcubacteria; Parcubacteria 4-related | |
| "Taylorbacteria" | RIF16 | CPR; Parcubacteria; Parcubacteria 4 | |
| "Tectomicrobia" | |||
| "Terrybacteria" | RIF13 | CPR; Parcubacteria; Parcubacteria 2 | |
| "Torokbacteria" | CPR; Parcubacteria; unclssified Parcubacteria | ||
| UBP-1 | |||
| "Uhrbacteria" | CPR; Patescibacteria; Parcubacteria; Parcubacteria 1 | ||
| "Veblenbacteria" | RIF39 | CPR; Parcubacteria; Parcubacteria 1-related | |
| "Vogelbacteria" | RIF14 | CPR; Parcubacteria; Parcubacteria 4 | |
| "Wallbacteria" | RIF33 | ||
| "Wildermuthbacteria" | RIF21 | CPR; Parcubacteria; Parcubacteria 2 | |
| "Wirthbacteria" | CPR-related bacteria | ||
| "Woesebacteria" | CPR; Patescibacteria; Microgenomates | ||
| "Wolfebacteria" | CPR; Patescibacteria; Parcubacteria; Parcubacteria 3 | ||
| "Woykebacteria" | RIF34 | CPR; Microgenomates | |
| "Yanofskybacteria" | CPR; Patescibacteria; Parcubacteria; unclassified Parcubacteria | ||
| "Yonathbacteria" | RIF44 | CPR; Parcubacteria; Parcubacteria 4 | |
| "Zambryskibacteria" | RIF15 | CPR; Parcubacteria; Parcubacteria 4 | |
| ZB2 | OD1-ZB2 | CPR; Parcubacteria | |
| "Zixibacteria" | FCB group |